Question: If $x \oplus y = 4x^{2}+y^{2}$ and $x \bigtriangledown y = x-3y$, find $(-1 \oplus -6) \bigtriangledown 3$.
Explanation: First, find $-1 \oplus -6$ $ -1 \oplus -6 = 4(-1)^{2}+(-6)^{2}$ $ \hphantom{-1 \oplus -6} = 40$ Now, find $40 \bigtriangledown 3$ $ 40 \bigtriangledown 3 = 40-(3)(3)$ $ \hphantom{40 \bigtriangledown 3} = 31$.